The singers sing about the one song that occurs in every Broadway musical, and its defining features (incredibly long, changing musical keys, and extremely high notes). In the Broadway production of the musical, a chandelier appears above the singers, an additional parody of The Phantom of the Opera's famous song. At the end of the song, the singers hit a note so high that it seems to shatter the chandelier.
Once in every show
There's a song that goes like this
It starts off nice and slow
And ends off with a kiss
Oh this is the song that goes like this!